All of lore.kernel.org
 help / color / mirror / Atom feed
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Xiaoming Ni <nixiaoming@huawei.com>,
	linux-kernel@vger.kernel.org, benh@kernel.crashing.org,
	mpe@ellerman.id.au, paulus@samba.org,
	linuxppc-dev@lists.ozlabs.org, yanaijie@huawei.com,
	npiggin@gmail.com, ravi.bangoria@linux.ibm.com,
	mikey@neuling.org, aneesh.kumar@linux.ibm.com,
	haren@linux.ibm.com, wangle6@huawei.com
Subject: Re: [PATCH] powerpc:Don't print raw EIP/LR hex values in dump_stack() and show_regs()
Date: Mon, 21 Dec 2020 10:31:30 -0600	[thread overview]
Message-ID: <20201221163130.GZ2672@gate.crashing.org> (raw)
In-Reply-To: <2279fc96-1f10-0c3f-64d9-734f18758620@csgroup.eu>

On Mon, Dec 21, 2020 at 04:17:21PM +0100, Christophe Leroy wrote:
> Le 21/12/2020 à 04:27, Xiaoming Ni a écrit :
> >Since the commit 2b0e86cc5de6 ("powerpc/fsl_booke/32: implement KASLR
> >infrastructure"), the powerpc system is ready to support KASLR.
> >To reduces the risk of invalidating address randomization, don't print the
> >EIP/LR hex values in dump_stack() and show_regs().

> I think your change is not enough to hide EIP address, see below a dump 
> with you patch, you get "Faulting instruction address: 0xc03a0c14"

As far as I can see the patch does nothing to the GPR printout.  Often
GPRs contain code addresses.  As one example, the LR is moved via a GPR
(often GPR0, but not always) for storing on the stack.

So this needs more work.


Segher

WARNING: multiple messages have this Message-ID (diff)
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Xiaoming Ni <nixiaoming@huawei.com>,
	ravi.bangoria@linux.ibm.com, mikey@neuling.org,
	yanaijie@huawei.com, haren@linux.ibm.com,
	linux-kernel@vger.kernel.org, npiggin@gmail.com,
	wangle6@huawei.com, paulus@samba.org, aneesh.kumar@linux.ibm.com,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc:Don't print raw EIP/LR hex values in dump_stack() and show_regs()
Date: Mon, 21 Dec 2020 10:31:30 -0600	[thread overview]
Message-ID: <20201221163130.GZ2672@gate.crashing.org> (raw)
In-Reply-To: <2279fc96-1f10-0c3f-64d9-734f18758620@csgroup.eu>

On Mon, Dec 21, 2020 at 04:17:21PM +0100, Christophe Leroy wrote:
> Le 21/12/2020 à 04:27, Xiaoming Ni a écrit :
> >Since the commit 2b0e86cc5de6 ("powerpc/fsl_booke/32: implement KASLR
> >infrastructure"), the powerpc system is ready to support KASLR.
> >To reduces the risk of invalidating address randomization, don't print the
> >EIP/LR hex values in dump_stack() and show_regs().

> I think your change is not enough to hide EIP address, see below a dump 
> with you patch, you get "Faulting instruction address: 0xc03a0c14"

As far as I can see the patch does nothing to the GPR printout.  Often
GPRs contain code addresses.  As one example, the LR is moved via a GPR
(often GPR0, but not always) for storing on the stack.

So this needs more work.


Segher

  reply	other threads:[~2020-12-21 16:40 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-21  3:27 [PATCH] powerpc:Don't print raw EIP/LR hex values in dump_stack() and show_regs() Xiaoming Ni
2020-12-21  3:27 ` Xiaoming Ni
2020-12-21 15:17 ` Christophe Leroy
2020-12-21 16:31   ` Segher Boessenkool [this message]
2020-12-21 16:31     ` Segher Boessenkool
2020-12-21 16:42     ` David Laight
2020-12-21 16:42       ` David Laight
2020-12-21 17:12       ` Segher Boessenkool
2020-12-21 17:12         ` Segher Boessenkool
2020-12-22 13:45         ` Xiaoming Ni
2020-12-22 13:45           ` Xiaoming Ni
2020-12-22 17:29           ` Segher Boessenkool
2020-12-22 17:29             ` Segher Boessenkool
2020-12-22 17:45             ` Christophe Leroy
2020-12-22 17:45               ` Christophe Leroy

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201221163130.GZ2672@gate.crashing.org \
    --to=segher@kernel.crashing.org \
    --cc=aneesh.kumar@linux.ibm.com \
    --cc=benh@kernel.crashing.org \
    --cc=christophe.leroy@csgroup.eu \
    --cc=haren@linux.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=mikey@neuling.org \
    --cc=mpe@ellerman.id.au \
    --cc=nixiaoming@huawei.com \
    --cc=npiggin@gmail.com \
    --cc=paulus@samba.org \
    --cc=ravi.bangoria@linux.ibm.com \
    --cc=wangle6@huawei.com \
    --cc=yanaijie@huawei.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.